The pupil as a possible monitor of the autonomic nervous system

The pupil is innervated by the autonomic nervous activity. With the easiness of observation, it has been utilized as a possible monitor of the autonomic nervous system activity. In this paper, two possible methods for evaluating the sympathetic and the parasympathetic nervous activity are proposed. One of them is an improved version of the conventional method which has been developed and used by neuro-ophthalmologists to diagnose the autonomic nervous diseases. The other one employs the inverse dynamic model of the pupil muscle system. Validity of each method is confirmed by the drug experiment or comparison with directly measured autonomic nervous system activity to the pupil. Finally, the result of an application of the new method is described.